1. Field of the Invention
The present invention relates to a blank transferring apparatus best suitable for transferring a blank under the secondary pressing operation to a subsequent pressing step while turning over the same 180 degrees, or transferring such a blank to a subsequent pressing step through the changeover between the operation in which the blank is transferred while being turned over (referred to as "turnover transfer operation", hereinafter) and the operation in which the blank is transferred without being turned over (referred to as "non-turnover transfer operation", hereinafter).
2. Description of the Prior Art
In a typical conventional turnover apparatus of this kind, a retainer member for retaining a blank turns over a blank by a 180-degree rotation and then returns to the former position by a 180-degree reverse rotation. Therefore, the retainer member is required to rotate 360 degrees for one turnover operation; hence, the turnover speed is low. In addition, the blank taken out from a press by means of the arm of a handling device is supplied into the blank turnover apparatus while being lowered from the upper side and is then turned over by the retainer member upwardly with an end edge of the blank as an axis of rotation or with the center of the blank as an axis of rotation. Therefore, the turnover operation must be started after the arm of the handling device has escaped from the upper side of the blank turnover apparatus, which hinders any reduction in time for feeding the blank from the press in the previous step to the press in the subsequent step.
In the secondary pressing operation line, a conveyor or other transfer apparatus is usually employed in the case where there is a distance between the handling terminating point of the blank taken out from the press in the previous step by means of the handling device and the feed starting point of the blank to be fed to the press in the subsequent step by means of a feeder. Moreover, in the case where it is necessary to transfer the blank while turning over the same 180 degrees, a turnover apparatus is employed.
Accordingly, it is a conventional practice that when the blank is transferred as it is, i.e., without being turned over, an ordinary transfer apparatus is installed in the secondary pressing operation line; and when the blank is transferred while being turned over, the ordinary transfer apparatus is replaced with a turnover apparatus. In consequence, when the turnover transfer operation and the non-turnover transfer operation are frequently changed over from one to the other in one secondary pressing operation line, it is troublesome to effect the operation of replacing the transfer apparatuses with each other, and in addition, much time is required therefor, disadvantageously.